gravity gun?

When picking a gun pay attention to the CFM requirements of the gun versus the CFM capacity of the air compressor you are going to use. If you buy a gun with high CFM requirements and have a low CFM compressor the gun will not atomize the paint and you will have a rough texture finish.

Use minimum 3/8" inner diameter air hose. Small inner diameter air hose will not work.

As for HF guns there have been many different models of purple guns over the years and the model numbers and design have changed. Google the part number of gun you are considering and try and find reviews.

I have a HF 90977 purple/chrome gun, works great, requires a low 6 CFM @ 40 psi, but its no longer offered. I also have a new 68843 chrome HF gun but the CFM requirements are minimum 12 CFM @ 40 psi which is just above the capacity of my compressor. So that gun sits in the box till I get a higher CFM compressor OR I just want to shoot a single panel. I also have a new DevilBiss Plus gun I bought from autobody101.com which has CFM requirements below my compressor output so that is the gun I plan to shoot clear with.

Disassemble and clean gun after every use with Lacquer Thinner. HF sells a brush kit. This will keep the gun working correctly.

Also, very important to get high flow air coupling fittings like Milton V High Flow from amazon.com. High flow fittings allow the CFM to get to the gun so it can atomize the paint correctly. As a benefit they also dramatically improve impact gun power. Your standard box store air couplings and fittings will choke off air flow.

Practice on junk body parts to learn.

Just trying to pass along some of the lessons I have learned the hard way.....